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Presentation Details
| Comparative effectiveness of Apixaban and Rivaroxaban for stroke prevention in patients with obesity with atrial fibrillation: a retrospective cohort study Pedro Luiz L.B.Danielian1, Ursula M.A.de Matos2, Samantha J.Neeson1, Aarti H.Asnani1, Patricia Tung1, Rushad Patell1. 1Beth Israel Deaconess Medical Center, Boston, MA, USA.2University of Connecticut School of Medicine, Farmington, CT, USA |
Abstract
Background Rivaroxaban and apixaban are used at fixed doses for stroke prevention in atrial fibrillation (AF), although obesity, a frequent AF comorbidity, can alter drug distribution and metabolism. Emerging data suggest apixaban may be safer and similarly effective compared with rivaroxaban in the general population, likely related in part to differences in dosing frequency: rivaroxaban’s once-daily regimen yields a higher Cmax (peak concentration), whereas apixaban’s twice-daily dosing yields a lower Cmax. However, obese individuals often have a higher volume of distribution, and a higher Cmax could theoretically favor rivaroxaban by providing more reliable therapeutic levels. Currently, no head-to-head comparative data exist in obese populations to assess the pharmacokinetics of these agents. Objectives To compare thrombosis and bleeding risk in obese patients with AF treated with apixaban or rivaroxaban. Methods This was a retrospective cohort study using the TriNetX Research Network, which aggregates electronic medical records from 103 healthcare organizations. Obese individuals (body mass index [BMI] ≥ 30 kg/m2) with newly diagnosed nonvalvular AF receiving rivaroxaban or apixaban from 2012 to 2025 were identified. Exclusion criteria were mitral stenosis, cancer, prior venous thromboembolism, use of anticoagulants, or any study outcomes within 1 year prior to anticoagulation initiation (to avoid potential misclassification). The primary endpoint was ischemic stroke. Secondary endpoints included composite arterial thrombotic events (including ischemic stroke, ischemic heart disease, transient ischemic attack, and arterial thrombosis) and bleeding. Endpoints were identified using validated ICD-10-based algorithms. Cohorts were defined by first anticoagulation use (apixaban or rivaroxaban) and balanced with propensity score matching incorporating demographics, comorbidities, and concurrent medications. Cumulative incidences of thrombotic and bleeding outcomes at one year from anticoagulation initiation were computed and compared by log-rank test. A sensitivity analysis used alternative BMI cutoffs for obesity of 35 kg/m2 and 40 kg/m2. Results After matching, each cohort included 18,763 individuals. Mean age was 67 ± 11.40 years, 58.9% were male, mean BMI was 36.5 ± 6.54 kg/m2, 20.8% had diabetes mellitus, 11.8% had heart failure, and 46.2% had hypertension (Table 1). All covariates were balanced across cohorts, with standardized mean differences <0.10. Stroke rates did not differ between groups (2.4% vs. 2.6%; HR 0.90 [95% CI 0.79 – 1.02]). Rivaroxaban was associated with a significantly lower rate of arterial thrombosis (6.0% vs. 6.7%; HR 0.86 [95% CI 0.80 – 0.94]) but higher bleeding risk (9.3% vs. 7.9%; HR 1.13 [95% CI 1.05 – 1.21]) than those receiving apixaban. The sensitivity analysis with higher BMI thresholds yielded similar results, favoring rivaroxaban for thrombotic and apixaban for bleeding outcomes (Figure 1). Conclusions In this population-based study of patients with obesity and newly diagnosed AF, rivaroxaban and apixaban were associated with similar rates of ischemic stroke, but rivaroxaban was associated with lower rates of arterial thrombotic events, contrasting with prior studies showing similar efficacy in the general population. However, rivaroxaban carried a higher bleeding risk, consistent with earlier findings. Taken together, these results highlight a potential efficacy–safety tradeoff in this sub-population and underscore the need for dedicated comparative studies in obesity to guide clinical decision making.
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No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author.